Robert Voyksner (Presenter)
Bio: Dr. Robert D. Voyksner received his B.S. in Chemistry at Canisius College in 1978 and his Ph.D. at the University of North Carolina at Chapel Hill in 1982. He founded LCMS Limited and has been the President of the company since 2000. Under his direction LCMS Limited is working on technological advancements in LC/MS, offering solutions to unique problems by LC/MS/MS and offering training in LC/MS/MS. Dr. Voyksner is also an Adjunct professor at the North Carolina a School of Veterinary Medicine and at The University of North Carolina School of Pharmacy. Dr. Voyksner's research in mass spectrometry has resulted in over 100 publications. He has served on the Board of Directors for ASMS, organized 5 Montreux LC/MS Symposium and taught LC/MS courses at ASMS for nearly 30 years.
Authorship: Robert Voyksner (1), Jack Syage (1), Joseph Murray (2), Chaitan Khosla (3), Jennifer Sealey-Voyksner (1)
(1) ImmunogenX, Newport Beach, CA, United States, (2) Mayo Clinic, Rochester, MN, United States, (3) Stanford University, Stanford, CA, United States
This work is leading to a minimally-invasive diagnostic for celiac disease (CD) management as an alternative to an invasive and expensive biopsy. The method uses administration of a drug biomarker simvastatin that is strongly metabolized by the CYP3A4 enzyme on the villi of the small intestine. Therefore, its concentration in subsequently drawn blood samples, as measured by LC/MS, is directly related to villous health. Here we report new trial data conducted at the Mayo Clinic that substantiates data from an initial feasibility study and further refines the method for extracting SV Cmax from just two blood draw time points.
Although CD is effectively diagnosed in clinical practice, practical tools for monitoring the patient’s recovery do not currently exist; the only accepted means for monitoring the villous health of the small intestine is an invasive and expensive endoscopy procedure with biopsy This procedure is not effective at assessing the overall healing of villous atrophy.
Simvastatin (SV) is a commonly used medication that is considered safe and has been given to many millions of patients as a cholesterol reducing drug. SV is highly metabolized by CYP3A4 in the intestine. Monitoring SV metabolism is postulated to represent an overall measure of the health of the intestinal mucosa. This was demonstrated by a pilot longitudinal study of CD patients in India . Data presented here describe how a simple blood measurement of SV metabolites using LC/MS can help millions who suffer with CD.
A cross-sectional trial was conducted for 20 newly diagnosed and 10 long-term treated CD patients as well as 10 healthy non-CD control patients at the Mayo Clinic (Rochester, MN). SV was administered orally to the patients and blood (2 mL) was drawn at five timepoints (0, 30, 60, 120, and 180 min). Quantification of SV and its major (reversible) metabolite simvastatin hydroxy acid (SVA) was accomplished using isotopically labeled standards (d6 analogs of SV and SVA) on an Agilent 1290 LC system coupled to a 6530 qTOF, operated in electrospray positive ion mode for SV and negative ion mode for SVA, using 2 GHz extended dynamic range mode and auto MS/MS mode. For full scan MS spectra, the TOF converted the mass range of m/z 300-1300 in 0.5 s. Targeted MS/MS masses allowed the acquisition of MS/MS spectra for SV, SV-d6, SVA and SVA-d6 using their respective exact masses.
The Cmax values for SV and SVA were compared to approximations using various model fits to just two timepoints (60 and 120 min) to assess the accuracy for a practical diagnostic. These models included time-point average, maximum time-point and Gaussian fit using a fixed width parameter best representing the average of all pharmacokinetic absorption and elimination profiles.
A distinct differentiation in SV Cmax values was observed in the expected trend of high values for newly diagnosed CD, low values for healthy non-CD controls, and intermediate values for long-term treated CD. A Gaussian two-point fit for Cmax gave ROC plots (sensitivity vs. specificity) that nearly matched that for the full-time period Cmax determination. An unexpected result was that SV levels for long-term gluten-free diet (GFD) treated patients were relatively higher than expected based on a previous feasibility study suggesting that this patient population may not be on strict GFDs. Furthermore, the SV levels reflecting villous health increased (poorer villous health) for patients with increasing weight further suggesting that GFDs may not be sufficiently under control for removing gluten.
Our trial at the Mayo clinic is continuing into a longitudinal stage where these patients are being tested 6 months later to determine whether newly diagnosed patients on a GFD are experiencing improved villous health, as measured by the SV levels. By repeating the measurement on all healthy patients, we can also obtain a measure of the intrapatient variability of the diagnostic in patients where no changes to villous health are expected.
Conclusions & Discussion
This work substantiates the previous successful feasibility study indicating that monitoring the metabolism of SV in blood can be a useful diagnostic for CD patients on a gluten-free diet and affords a minimally-invasive and economical means to monitor intestinal recovery without resorting to biopsy.
References & Acknowledgements:
 Moron B, Verma AK, Khosla C et al. CYP3A4-catalyzed simvastatin metabolism as a non-invasive marker of small intestinal health in celiac disease. Am J Gastroenterol 2013; 108: 1-8.
|Board Member||yes||Board of directors of Flamentera AG, Advanced Telesensors, and Appellation Ventures|
|Stock||yes||ImmunogenX, Advanced Telesensors, Appellation Ventures, and some venture funds|
IP Royalty: no
|Planning to mention or discuss specific products or technology of the company(ies) listed above:||